The support structure of a vehicle includes a large number of support elements, for example side members and cross members as well as pillar elements which, depending on arrangement, can be connected to one another in various ways. Usually, the support elements are produced from hollow profiles that are opened or closed in the cross section, which enclose a hollow space. It is consequently opportune to arrange assembly units in this hollow space in order to be able to utilize the existing space in a vehicle which is naturally limited.
When utilizing the hollow space that is enclosed by the hollow profiles for arranging assembly units, for example an inertia belt reel, the following disadvantages may be experienced. On the one hand, arranging an assembly unit in a hollow space involves increased mounting expenditure, and on the other hand it is necessary to provide openings in the wall of the hollow profiles in order to introduce the assembly unit into the hollow space. Providing these openings however results in a weakening of the support element concerned, so that additional stiffeners and/or higher material thicknesses have to be provided or the dimension of the support elements have to be increased in order to again offset this weakening. However, by doing so the construction of the vehicle is rendered more complicated on the one hand and the weight of the vehicle is increased on the other hand, which, as part of the efforts of keeping the production simple and to reduce the fuel consumption, is counterproductive. In the case that the support element concerned is dimensioned larger, more installation space is additionally required so that the trunk or the occupant space is rendered correspondingly smaller.
DE 102 12 336 A1 describes a support element with an opening through which an assembly unit can be introduced into the hollow space. The weakening of the support element is offset in that the assembly unit is arranged fixed on a flat support plate. The support plate completely covers the opening and extends beyond it. In the overlapping part, the support plate is screwed to the support element. The support plate, on which the assembly unit is preassembled, is screwed onto the support element from the outside so that there is no interaction between the support plate and the boundary faces. As a result, the loads and stresses are transmitted to the support plate via connecting means such as screws so that the connection means are subjected to shearing, which can result in a failure of the connection. Here, the support plate is embodied continuously so that the selection of the possible assembly units that can be introduced into the hollow space with the solution described in DE 102 12 336 A1 is limited.